Variable-speed transmission



June 6, 1950 D. L. LOT-rs VARIABLE SPEED TRANSMISSION Filevzl,l May. 6,1 19484 INVENTOR. .D6LBGP1T L, LOTTS Htorme f June 6, 1950 D. L. LoTTs 2,510,749

' VARIABLE SPEED TRANSMISSION 5 sheets-sheet 2 Filed may 1948 FIG. 6

INVENTOR.

.DGLBSRT L'.. LOTTS f Patented `une 6,r 1950 f UNITElDf Sini.las oFF-ICE I 2,510,749 e VARIABLE-Seann TRANsMISSfQN Delbert L.vrLottsKent Ollio Application May c, 1948, serial Np. k25,411

V1.1 ClaimsP l This invention relates. to speed reducers and variable speed transmissions, and, more particularly, is concerned with mechanisms of this. type adapted to reduce driving shaft speeds substantially and throughout relatively wideA limits.

Heretofore, v'various speed reducers. and variable speed transmissions have been provided, but all knownrdevicesare opento one or. more objections heing, for. example, relatively expensive initially, not providing the desired. speed ratios or variance, wearing objectionahly in use, having slippages present, or requiring high maintenance.

It is the general object of my invention to avoid and overcome the foregoing and other difiiculties of and objections to` known devices by the provision of a speed reducer and/or. variable transmission which is relatively inexpensive ini,- tially, will effect desired speed changes, between a driving and a driven shaft, which can be readily adjusted while in use to change speed ratios over wide limits, which is quiet and relatively light, and which will operate over long `periods o f vtime with substantially no maintenance or wear problems. Y ,Y Another object of my invention is the provi-l sion of a speed` reducer forY greatly reducing speeds, and costing and weighingless than conrentional reduction gearing.

nother object of my invention isv tol provide a varable'speed transmission'of icompac'tsize and .Gbmparatively low cost, but' adapted to operate at high efficiencies Yover a wide range of speed, andwhiclhcan be readily adjusted duringr the voperation of the transmission.

'I he foregoing objects of my invention, and other objects which will become apparent as. the description proceeds, are achieved'by the provision of a variable transmission including a driving shaft, a driven shaft, a conical eccentric tapering' to a substantially cylindrical portion,

andY driven by the driving' shaft, followers en- 'gagng'with substantially diametrically opposed 'portions of the eccentric, means for effecting relative axial nlovement between the eccentric andthe followers to` control the throw of the eccentric on the followers, and means for alternately transferring the linear movement of the followers to theV driven shaft in the form of rotary movement. Preferably the last named means include a pair of opposite hand worm 'gears carried by the driven shaft, a pair of worms of opposite hand associated with and carried by each follower, and freely rotatable in one direction only, means locking the worms against rotationin the'opposite direction, said worms engagng' with the `worm gears at, substantially. op,- posed'y portions thereof, and. means resiliently holding' the followers. towards Aeach other and againsttheeccentri'c.

lf the variable specdftransmissionis to be util.- izecl solely. as av speed reducer of xed ratio between thedr-ivingand driven shafts, Ythen it .is unnecessary toinclude means for effecting rela.- tive axial movement .between the .eccentric vand the fol-lowerstocontrolthe throwof the veccentric on the followers.

For a better understanding. ofmy invention, reference 'should be. had tothe accompamring drawings, wherein,

' Figi l'is alongitudinal, verticaLcross-Sjectional view through a typical apparatus incorporating the principles ofV my invention;VV

'.Eig. 2 is a transversavertical, crossfsectional View taken substantiallyon line'lI-II ofFig. l. vand illustrating .details of the means for` trans.- -fe'rring l.the linear movement. of the eccentric followers to rotaryv movement onthe. driven shaft;

Eig; 3Lis a transverse', vertical, cross-sectional view taken substantially on line IIL-III of Fig. 1, and-illustratingv details of the. mountingof one of the eccentric followers;

Fig. fiisa transverse, vertical, cross-sectional View .taken substantially. on line VIV-IV of Fig. l. and illi'istrating .details .of .the structure .and VV'mounting ofthe second y:fnllower for the. eccentric;

Fig. 5 is a transverse, vertical, cross-sectional AView takensubsta'ntially. on line .V-V of. Fig, ,1; and` illustrating .details of .the lresilient.k means for holding the cam followers towards the Veccentric;` Y

' Fig. 6 .is a transverse, .substantially vertical, cross-sectional view taken substantially on line lVL--VVI of Fig. `1, andY onan enlargedscale, and illustrating details of the driven shaft;

Fig? is atransverse. vertical, cross-sectional view! taken ,substantially on line VII-VII of Fig. 1, and illustrating details .of thev driving shaft, including. means for'k changing. the eective. throw oftheeccentrici Fig. 8 is a vertical, cross-sectional view, taken substantially on line VIII-VIII of Fg.- '7, and ilrlustrating furtherdetails of the meansfor changing the effective throw. of the eccentric; and.

Fig. 9 is an enlarged.ermiview of the eccentric and its manner .of construction, the driving lshaft'supporting Vthe eccentric being shownin .cross-section? In the drawing, the numeral .l0 indicates. generally Va casing, which obviously can be :con-

.'U-shaped bracket 56. ...on parallel rods 58 and `60 which have shoulder structed in a number of ways, but which usually includes integrally formed holddown lugs I2, removable, gasketed end plates I4 and a removable cover |6.

Journaled in the casing, and transversely thereof, is a driving shaft, indicated as a whole by the numeral I8, this shaft being usually journaled by means of roller bearings 20 positioned in caps 22 and 24 removably secured to the casing by screws 26. Gasket means (not shown) may be associated with the bearing 26 in cap 22. The shaft I8 is adapted to be driven, as by motor 30, through a suitable drive, such as V-belts, or the like, although gearing 32 has been illustrated as connecting the motor 30 to the shaft I8.

ISplined to the shaft I8 is a tapered or conical eccentric 34, the splines being indicatedV at 35, s that the eccentric will turn with the driving shaft I8, but is free to move axially thereof. The construction and operation 'of the eccentric 34 will bek described in greater detail hereinafter. The eccentric 34 is adapted to be adjustably positioned at any desired point Ialong the driving shaft I8, and to this end a yoke 36, best seen in Figs. 7 and 8, is rotatably mounted on bearings 38 `for free rotary movement with respect to the eccentric, but with a nut 48 preventing relative axial movement between the yoke 36 and the eccentric 34. The upper end lof the yoke 36 is provided with a tapped opening 42 into which is threaded a screw 44, which is journaled transversely of the casing, and with one end of the screw '44 having 'a crank 46 attached thereto, so that when the crank 46 is turned the screw 44 will move the yoke 36 and eccentric 34 axially of the drivmg 'shaft I8.

Associated with the eccentric 34, and positioned within the casing I0, are followers 48 `and 50 which engage substantially diametrically opposed portions of the eccentric. As illustrated in Figs. l land 3, the follower 48 is mounted on a ball bearing 52 carried by a short shaft 54 received in a The bracket 56 is carried portions of increased diameter, and indicated by the numeral 62, against which the bracket 56' is Aadapted to be clamped by spacer tubes 64, end .plates 66 and 68, which :clamp the ends of the rod together, and nuts 'I0 screwed on the threaded 'ends of the rods 58 and 60 in the manner shown in Figs. l and 5. The left hand end of the rods 58 and `60, as seen in Figs. 1 and 2, have a bridg- .ing plate 12 which engages with the left hand end ofthe enlarged shoulder portions 62, each rod rotatably receiving a worm I4 of opposite hand, and

end plate 16 holds the worms in position, the ends .f the rods being threaded to receive locking nuts The structure just described, including the follower 48, bracket 55, rods 58 and 60, Worms 14,

Sand end and bridging plates, is rotatably supported for reciprocating movement. This. is

achieved by providing transverse shafts 80 and 82 vin the bottom of the casing I0, each'shaft having an eccentric hub 84 and 86 respectively secured to it, the hubs 84 and 86 rotatably carrying wrings 88 and 60, the rings 88 and 90 being grooved 4 and 82 from outside the casing, or by turning the hubs (which may be fixed to the shafts by set screws) with respect to the xed shafts. The angular adjustment of the eccentric hubs will raise c-r lower the plane of reciprocating movement lof the rods 53 and 60, all as hereinafter more particularly described.

The follower 50 is mounted in a similar but reversed manner. More particularly, the follower 50 is carried on a ball bearing 9-8 secured to a shaft |00 carried by an inverted U-shaped bracket |82, the lower ends of the bracket |02 being grooved at |04 to slide on the upper surfaces of sleeves 64. The upper end of the bracket |02 is slidably received on rods |06 and |08, which have enlarged shoulder portions |0 against which the bracket is clamped by means of sleeves ||2 and an end plate I4 held in position by nuts ||6 received on the threaded ends of the rods |06 .and |08. In conjunction with the end plate ||4, it is to be noted that the end of a leaf spring ||8 engages with the end plate, the leaf spring being clamped between the end plates 66 and r68 carried by the rods 58 and 60, with the leaf spring ||8 functioning to resiliently urge the followers 48 and 50 towards ea-ch `other and into engagement with the eccentric 34.

A bridging plate |20 abuts against the left hand end of the enlarged shoulder portions |0 of the rods |06 and |08, and the rods rotatably receive worms |22 of opposite hand, which are held in position on the rods by an end plate |24 and locking nuts |26 received on the threaded ends of the shafts |06 and |08.

The plane of reciprocating movement of the rods |06 and |08, and the structure carried thereby, is controlled by shafts |36 and |32 secured transversely of the casing I0, each shaft having an eccentric hub |34 and |36, respectively, secured thereto, the eccentric hubs rotatably carrying rings |38 and |40, each of the rings being formed with grooves |42 (see Fig. 6), which siidably engage with the enlarged shoulder portions ||0, and with the sleeves ||2 of the rods |06 and |08. The angular relation of the shafts |38 and |32 with respect to the casing can be controlled to effect the angular adjustment of the eccentric hubs |34 and |36, in the manner heretofore described in conjunction with shafts 88 and 82, or the position of the eccentric hubs |34 and |36 can be changed angularly with respect to fixed shafts, all to adjust the plane of recprocation of the rods |06 and |08 and the mechanism carried thereby.

Positioned between the worms |22 and '14, yand extending transversely of the casing I8, is a driven shaft |46, which as illustrated in Figs. l, 2 and 6 is journaled at one end by a bearing |48 in the casing with the other end of the shaft extending out through the side of the casing through a bearing and packing means |50, and having a pulley or -other driving means |52 associated therewith. Keyed to the driven shaft |46 is a double worm gear |54, and the worm gear may be axially positioned on the driven shaft |46, as by the provision of a shoulder |56 on the shaft, and a lock nut |58 held in place by a set screw |60 to hold the worm gear |54 tightly against the shoulder |56, locking keys between the gear and shaft being indicated by the numeral |62. The double worm gear |54, as best seen in Fig. 2,'is formed with oppositely inclined Worm gear teeth |64, with which the opposite hand worm gears 'I4 engage at the bottom of the gear, and the oppor armere' siterhand worms vI 232 engage 'atithe'topfof the Worm .'.gear.|'54.

:Associated with the `worms 14, :and with the 'worms `|22 are meanswhich .permit the free .ro- -tationof the worms in one direction, but which vlock to 'prevent the rotation 'of the worms in the fopposite direction. More particularly, aand Shaving reference'to Figs. 1 and 6,'a3v-.fedge MGH-.ispos'itioned resiliently between -the "worms 14, this wedge having its wedging surfacesiatla'n inclusive angle of between 'approximately `seven ide'grees Aand fourteen degrees, and rbeing resiliently :held Yby a loop of spring wire licarried -by `lthe end .plate le. The spring |68 Alightly urges theiwed'ge |65 into position between-the worms 14,1and'does .not interfere with'thewvorms T4 turning .inthe-di'- rection shown by the arrows in Figx, but `'when .the worms 14 attempt to turn in the oipposite-direction, the wedge vH56 locks between 'the worms vand prevents their frotation. In a like manner, wedge |79 is resiliently heldbyxlooped wire-sprilfl?,r l2 down between I-the :worms 22, the lspring loop |12 being supported on theend plate |24.

:A :brief `.description ofthe operation of the'ap- :paratus as described heretofore is in order. .Assuming the .motor v30 is Ioperating to drive the idriving shaft 18, the rotation =of :this shaft will rotate the veccentric -cone 314. With fth'e parts .1in the position shown -.in.rFig. -1 .of ther-:drawings #as v:the eccentric cone 34 turns, it will :move ythe :follower 48 positively tothe lefta-,distancefequal to ithe throw of the eccentric VIcone. During the movement of the follower to the deft, thezwedge |68 will lock between the worms |4 inasmuch Vas the tendency of thewormsLis to lrotate f inztlfiedi-m rection opposite to lthe arrows shown -in iliig. 6. .-Inasmuch as the wormsfll ,cannot'turrr -they 1:will act as va rack todrivethe worm gear ifi-llzand thus the drivenshaft |45 through an farproportional fto thethrowof .the eocentricfcone 54. fAs-the high .part of the eccentric cone .passes Ethe Yfollower 45, Vthe follower will begin ,tomoveto'the right under 'the influence of vthe fleaf spring |:,|S,'and '.atgthis time, `the worm-s 14 rotate :freely intheropposite direction, or in thedirectionzshownrbyfthearrows in lig. 16. The vwedge H56 does not interfere "with this rotation of the worms, andfthexworms M .rods 58 and 'supporting them, vand the vwhole ias- -sembly supporting `the .follower '48 :moves '-.to the right back to the position shown in Fig. .1, :the worms :i4 turningfreely on the rodsjiandfll to permit'this action. K:Ifithe ffollow`erv'48 .andits zas- .'sociated `mechanism alone were iutilized :in :the Altransmission, a continuous .rotary .movement .imparted `to the driving Ashaft -|'8 would result `in stepped -Aforward movement of lthe .driven :shaft #4e :interspersed .with a short dwellbe'tweenfeach :stepped :forward movement, :the period-of dwell 'being'substantially equal tothe periodf'of forward movement :In-:order to impart continuous rotary motiont'o theiidriven shaft Ide, the second .follower sand Aits-associated mechanism is utilizedrandperforms irl-exactly the same manner, but :in the 'periods rof .dwell .of the mechanism `.associated iwith the fol- .lower 48. Specically, :and .having reference to ZFig. i1, as the follower Ezmoves'ftoitheleft fdllring thestartfof the rotationaof ttheeeccentricicone .34 from the position showniin il, V'the 'worms :|222 rrevolve .freely :on .the .rods |06 sand |il18 Pand turn freely with .the wormgear 454, .thefoll'ower 56.1fol- .flowing the eccentric `cone 34| under lthe .-actionlio'f the Aleaf. spring iii. However,fafter'theccentrie cone 34 has been moved through nneihundrted 5 ".t'o ftheright `then the Wedge .i1-.0 locks between the v -worms |22, tto prevent `their rotation, .and fduring the movement to -zthe Vrightrof `the :follower 45|) the-worms 22 act as yatrack-.torotate the'wform ='gear |`54 and 'driven yshaft |48 through .an -f'arc `:eq-ual to the arc imparted by the follower 48.and 'Worms 14. Theresult is acontinuousrotation of *the Adriven shaft |"46 in direct :response toithe `throw ofthe eccentric cone 34.

In order to change the speedfratio betweenithe driving shaft I8 and the driven shaft |4,.'it2is1only .-"necessary .to fopera'te the fcrank '46 to rotateiscrew 44 .land move fyoke 3.6 and the :associated eccentric: fcone .34 lengthwise of the ldriv'ing shaft AHl ltoi'ine' crease orfd'ecreasethe throw 4of .the eccentric cone -34. Thus, relatively wide rspeed'rati'os can `ib'e 'obtained. f

Having 'more particular .reference Snow toFig. 9 `of the drawingswhich .shows ingreater detail :the construction of Vthe eccentric cone 34,fit will lunderstood 'that Fig. '.9 .is an send .elevaticnfo'f the -eccentric cone looking Vat the smallfend thereof. -It'will first be recognized .that'theismall endvzo'f fthe eccentric cone, .designated :by the numeral {34%,2is substantially :circular with .no veccentric action `whatsoever. The large .endof thefeccen'tric cone, designated by the :numeral :34kg can :be .fmade :to .have an .eccentric vthrow of vup to .three of an inch or more fwhereby .speeds approaching a one to one drive between `the .driving and .the .driven .shaftcan be obtained, ,dependent upon the :dimensions .of :the remaining .parts of lthe .apparatus, theipitch .of thevworms,'and the like. .-I-Iowik ever, the .apparatus is more usually adapted to .sizable speedreduc'ti'on -toadriven shaft .and variance .ofthe speed of :the .driven shaft. =Of course, when the followers '48 .and 5B are positioned 1in association withthe substantiallycircular end 31%a of the .eccentric cone, lthere twill be no .rotationiait all of the drvenshaft |45.

Having further .reference .to Eig. 9 o'fftherdraw'-I gings, l:at .the .pointA fof the fecc'entric fc'one, :this :is vparallel .tolthe axis 'of the driving `shaft 1v.the full length of the eccentric. .From point A to :point 'B there .is `a relatively quick rise in the Ieccentric to take iup zany lost .motion iin the apparatus. From point Btopoint Cthere is aconstantriselin the .eccentric vper the: angular displacement ther'ee of. From point C to point D, the cam is contoured to keep lin contact .with'thefollowenand to keep `.the follower from jumping off of the eccentric, during the change in direction of motion lof 'the follower. From point .D .to-.point E .thereis fa unieA 5form angular descent, and :from point-E to point A there is :a slower angular descent to bring 'the eccentric backto the starting pointA. Ane'ccena Ltric=designed in the mannerfdescrbed provides fe.

lrelatively noiseless and-satisfactorily-quiet opera-- tion. .Throughout the specification .and :claims the member 34 hasbeen termed aneccentric. vActually it ,might better be described as acamor fa conical cam of the fspecial shape and fstruoture described. However, regardless lof 1whe'ther lthis member is called .a @amor an eccentric, its shape Aand function will be understood from'thefforelgcing description.

From the foregoing, .it twill `=be vr'ecl'lgnized that .the various objects of my 4invention .has been achieved 'by "the 'provision :of fa speed reducer and/or variable speed vtransmission characterized by simplicity, inexpensiveness, long life, :a -wide variety of speed'changes, compactnessf'and .light weight. 'The apparatus :is adapted to ltunetion over :long :periods `A.of time with substantially lreighty :degreeaaandiis zreadyito moverme .follower 1751110 i'attention or maintenance problems-ut being understood that the casing-l is provided ,with a lubricating oil to a depth desired. Adjustments can be made from the outside of the casing,` both ,with respect to speed changes and wear take-up.

While in accord with the patent statutesone embodiment of my invention has been illustrated and described in detail, it is to be particularly understood that I am not to be lnnited thereto or thereby, but that the scope of my invention is defined in the appended claims.

I claim:

1. A variable speed transmission including a driving shaft,` a driven shaft, a conical eccentric tapering to a substantially cylindrical portion and driven -by the driving shaft, followers engaging with substantially diametrically opposed portions of the eccentric, means for effecting relative movement in an axial direction between the eccentric and the followers to control the throw of the eccentric on the followers, a pair of opposite hand Worm gears carried by the driven shaft, a pair of worms of opposite hand associated with and carried by each follower and freely rotatable in one direction only, means locking the worms against rotation in the opposite direction, said worms engaging with the worm gears at substantially opposed portions thereof, and means resiliently holding the followers towards each other and against the eccentric.

2. A variable speed transmission including a driving shaft, a driven shaft, a conical eccentric tapering to substantially a cylindrical portion and driven by the driving shaft, followers engaging with substantially diametrically opposed portions of the eccentric, means for effecting relative movement in an axial direction between the eccentric and the followers to control the throw of the eccentric on the followers, a pair of opposite hand worm gears carried by the driven shaft, a pair of worms of opposite hand associated with and carried by each follower and freely rotatable in one direction only, means locking the worms against rotation in the opposite direction, said worms engaging with the worm gears at substantlally opposed portions thereof, means resiliently holding the followers towards each other and against the eccentric, and means for adjustd ing the clearance between the worms and wor gear.

3. A variable speed transmission including a driving shaft, a driven shaft, a conical eccentric tapering to a substantially cylindrical portion and driven by the driving shaft, roller followers engaging with substantially diametrically opposed portions of the eccentric, means for effecting relative movement in an axial direction between the eccentric and the followers to control the throw of the eccentric on the followers, worm gear means carried by the driven shaft, worm means associated with and carried by each follower .and freely rotatable in one direction only, wedge means locking the worm means against rotation in the opposite direction, said worm means engaging with the worm gear means at substantially opposed portions thereof, and means resiliently holding the followers towards each other and against the eccentric.

4. A transmission including a driving shaft, a driven shaft, an ecentric driven by the driving shaft, followers engaging with opposed portions of the eccentric, means for eecting relative movement in an axial direction between the eccentric and the followers to control the throw of the eccentric on the followers, a pair of opposite hand Worm gears carried by the drivenv rof the eccentric, a pair of opposite hand worm gears carried by the driven shaft, a pair of worms of opposite hand associated with and carried by each follower and freely rotatable in one direction only, means locking the worms against rotation in the opposite direction, said worms eng'aging with the worm gears vat substantially opposed portions thereof, and means resiliently holding the followers towards each other and against the eccentric.Y

6. A variable speed transmission including a driving shaft, a driven shaft, a conical eccentric driven bythe driving shaft, followers engaging with opposed 4portions of the eccentric, multiple wormgear means carried by the driven shaft, multiple worm means associated with and carried by each follower and freely rotatable in one drection only, means locking the worm means against rotation in ther opposite direction, said worm means engaging with the worm gear means at substantially opposed portions thereof, and means resiliently connecting the followers together andA holding the followers towards each other and against the eccentric. Y

7. A speed changer including a driving shaft, a driven shaft, a conical eccentric driven by the driving shaft, a follower engaging with the eccentric, a pair of opposite hand wormvgears carried by the driven shaft, a pair of opposite hand `worms associated with and carried by the follower and engaging with the worm gears, said worms vbeing freely rotatable in one direction, a wedge urged into position between the worms to prevent rotation of the worms in the opposite direction, and means for adjusting the eccentric axially of the follower.

8. A speed changer including a driving shaft, a driven shaft, an eccentric driven by the driving shaft, Aa follower engaging with the eccentric, a pairv of opposite hand worm gears carried by the driven shaft, a pair of opposite hand worms associated with and carried by the follower and engaging with the worm gears, said worms being freely rotatable in one direction, and a Vwedge urged into position between the worms to prevent rotation of the Worms in the opposite direction. 9. A Variable speed transmission including a driving shaft, a driven shaft, a cone eccentric splined to the driving shaft, means for controllingtheY axial .position of the eccentric on the driving shaft,a frame slidably supported for reciprocating movement on one side of the eccentric, a frame slidably supported for reciprocating movement onthe opposite side of the eccentric, a follower mounted on each frame, resilient means connecting the frames and tending to hold the followers against opposite sides of the eccentric, means for separately adjusting the plane of reciprocating movement of each frame, a driven shaft positioned ,between Vthe frames, and means for converting the reciprocating movement of the frames ,to Vrotarymovement in the same direction tothe driven shaft.

10..,A vvariable speed. transmission including :a

driving shaft, a driven` shaft, a cone eccentric splined to the driving shaft, a frame slidably supported for reciprocating movement on one side of the eccentric, a frame slidably supported for reciprocating movement on the opposite side of the eccentric, a follower mounted on each frame, resilient means connecting the frames and tending to hold the followers against opposite sides of the eccentric, means for separately adjusting A the plane of reciprocating movement of each 10 resilient means connecting the frames and tending to hold the followers against opposite sides of the eccentric, a driven shaft positioned between the frames, and means for converting the reciprocating movement of the frames to rotary movement in the driven shaft.

DELBERT L. LOTTS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,812,460 Wellton June 30, 1931 1,954,767 Foster Apr. 10, 1934 FOREIGN PATENTS Number Country Date 23,978 Denmark Jan. 25, 1908 

